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Featured Application: This training regimen can be used as a time-efficient protocol for people with lower levels of aerobic fitness to kickstart their fitness journey. The training loads applied can be used as initial mesocycle loads for untrained participants, noting that, through effective periodization, the HITT intensities will periodically increase to provide an ongoing adaptive stimulus. Further, for aerobically trained individuals (>40 mL/kg/min), we suggest that this program be modified by increasing the prescribed training intensities to induce a sufficient stimulus to increase their baseline strength and aerobic parameters. An alternative use of this intervention is as a short (off-/pre-season) training regimen within sports clubs to boost strength and endurance parameters through a brief, but intense, time-efficient training approach. Finally, the described intervention could be implemented in occupational settings (e.g., fly-in–fly-out work camp labour workers in mines), where the benefit from incorporating a systematic training regimen, especially when the time devoted to exercise is limited, can lead to general health benefits. There is conflicting evidence on whether concurrent aerobic endurance and resistance training (RT) leads to synergistic enhancements in aerobic capacity and muscular strength or causes interference, limiting performance gains. We developed a concurrent training (CT) intervention, including full-body dynamic RT combined with high-intensity interval training (HIIT), on a cycle ergometer to determine whether a brief CT intervention is beneficial to both muscular strength and aerobic capacity. In an exploratory pilot study, participants (n = 10; male = 4) undertook a four-week CT intervention consisting of RT, including six compound movements (bench press, squat, deadlift, Pendley row, squat jumps, and rack pulls), plus cycle HIIT. The pre-/post-intervention improvements were assessed via bench press and leg press 3RM testing, an isometric mid-thigh pull, a countermovement jump, and the change in the relative V ˙ O2max. We observed significant (p < 0.1) increases in the bench press (6.4%), leg press (6.7%), IMTP (11.1%), and relative V ˙ O2max (7%) results. Interestingly, the participants with the highest pre-intervention relative V ˙ O2max demonstrated no performance improvements. These pilot test results suggest that CT is an effective strategy that enables synergistic enhancements that can be observed with very low training volumes. This suggests that CT is an effective strategy for improving muscular strength and aerobic endurance in non-elite physically active individuals. [ABSTRACT FROM AUTHOR]

In contrast to their exercise-trained counterparts, the maximal oxidative rate of skeletal muscle in sedentary humans appears not to benefit from supplemental O2 availability but is impacted by severe hypoxia, suggesting a metabolic limitation either at or below ambient [O.sub.2] levels. However, the critical level of [O.sub.2] availability at which maximal metabolic rate is reduced in sedentary humans is unknown. Using [sup.31]P magnetic resonance spectroscopy and arterial oximetry, phosphocreatine (PCr) recovery kinetics and arterial oxygenation were assessed in six sedentary subjects performing 5-min bouts of plantar flexion exercise followed by 6 min of recovery. Each trial was repeated while breathing one of four different fractions of inspired [O.sub.2] ([MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]) (0.10, 0.12, 0.15, and 0.21). The PCr recovery rate constant (a marker of oxidative capacity) was unaffected by reductions in [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII],remaining at a value of 1.5 [+ or -] 0.2 [min.sup.-1] until arterial [O.sub.2] saturation ([MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]) fell to less than ~92%, the average value reached breathing an [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] of 0.15. Below this [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], the PCr rate constant fell significantly by 13 and 31% to 1.3 [+ or -] 0.2 and 1.0 [+ or -] 0.2 [min.sup.-1] (p < 0.05) as [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] was reduced to 82 [+ or -] 3 and 77 [+ or -] 2%, respectively. In conclusion, this study has revealed that [O.sub.2] availability does not impact maximal oxidative rate in sedentary humans until the [O.sub.2] level falls well below that of ambient air, indicating a metabolic limitation in normoxia. oxidative capacity; [sup.31]P-magnetic resonance spectroscopy; exercise

It may be advisable to perform sequential magnetic resonance image (MRI) scans on the brains of infants with shaken baby syndrome (SBS) to evaluate the possibility of long-term injury. MRI scans give a cross-sectional picture of body tissues and their chemical activity. Several MRI scans were performed on three infants with SBS in the days following their injury and four to five months later. The infant with near normal brain chemical activity at five and seven days after injury did not have any evidence of long-term damage on the five-month MRI scan. The infants with abnormal activity one week after injury had long-term brain damage., Objective. The purpose of this study was to use proton magnetic resonance spectroscopy (MRS) as a metabolic assay to describe biochemical changes during the evolution of neuronal injury in infants after shaken baby syndrome (SBS), that explain the disparity between apparent physical injury and the neurological deficit after SBS. Methodology. Three infants [6 months (A), 5 weeks (B), 7 months (C)] with SBS were examined repeatedly using localized quantitative proton MRS. Examinations were performed on days 7 and 13 (A), on days 1, 3, 5, and 12 (B), and on days 7 and 19 (C) posttrauma. Long-term follow-up examinations were performed 5 months posttrauma (A) and 4.6 months posttrauma (B). Data were compared to control data from 52 neurologically normal infants presented in a previous study. Results. Spectra from parietal white matter obtained at approximately the same time after injury (5 to 7 days) showed markedly different patterns of abnormality. Infant A shows near normal levels of the neuronal marker N-acetyl aspartate, creatine, and phosphocreatine, although infant C shows absent N-acetyl aspartate, almost absent creatine and phosphocreatine, and a great excess of lactate/lipid and lipid. Analysis of the time course in infant B appears to connect these variations as markers of the severity of head injury suffered in the abuse, indicating a progression of biochemical abnormality. The principal cerebral metabolites detected by MRS that remain normal up to 24 hours fall precipitately to ~40% of normal within 5 to 12 days, with lactate/lipid and lipid levels more than doubling concentration between days 5 and 12. Conclusions. A strong impression is gained of MRS as a prognostic marker because infant A recovered although infants B and C remained in a state consistent with compromised neurological capacity. Loss of integrity of the proton MR spectrum appears to signal irreversible neurological damage and occurs at a time when clinical and neurological status gives no indication of long-term outcome. These results suggest the value of sequential MRS in the management of SBS. Pediatrics 1997;99:4-14; shaken baby syndrome, traumatic brain injury, neuronal injury, magnetic resonance imaging, magnetic resonance spectroscopy., ABBREVIATIONS. SBS, shaken baby syndrome; MRI, magnetic resonance imaging; MRS, magnetic resonance spectroscopy; FSE, fast spin echo; NAA, N-acetyl aspartate; G, creatine and phosphocreatine; Cho, choline-containing compounds; mI, myoinositol; Lac/Lip, [...]

Strenuous exercise elicits transient functional and biochemical cardiac imbalances. Yet, the extent to which these responses are altered owing to aging is unclear. Accordingly, echocardiograph-derived left ventricular (LV) and right ventricular (RV) global longitudinal strain (GLS) and high-sensitivity cardiac troponin I (hs-cTnI) were assessed before (pre) and after (post) a 60-min high-intensity cycling race intervention (CRIT60) in 11 young (18-30 yr) and 11 middle-aged (40-65 yr) highly trained male cyclists, matched for cardiorespiratory fitness. LV and RV GLS were measured at rest and during a semirecumbent exercise challenge performed at the same intensity (young: 93 ± 10; middle-aged: 85 ± 11W, P = 0.60) pre- and post-CRIT60. Augmentation (change from rest-to-exercise challenge) of LV GLS (pre: -2.97 ± 0.65; post: -0.82 ± 0.48%, P = 0.02) and RV GLS (pre: -2.08 ± 1.28; post: 3.08 ± 2.02%, P = 0.01) was attenuated and completely abolished, in the young following CRIT60, while augmentation of LV GLS (pre: -3.21 ± 0.41; post: -3.99 ± 0.55%, P = 0.22) and RV GLS (pre: -3.47 ± 1.44; post: -1.26 ± 1.00%, P = 0.27) was preserved in middle-aged following CRIT60. While serum hs-cTnI concentration increased followingCRIT60 in the young (pre: 7.3 ± 1.6; post: 17.7 ± 1.6 ng/L, P < 0.01) and middle-aged (pre: 4.5 ± 0.6; post: 10.7 ± 2.0 ng/L, P < 0.01), serum hs-cTnI concentration increased to a greater extent in the young than in the middle-aged following CRIT60 (P < 0.01). These findings suggest that functional and biochemical cardiac perturbations induced by high-intensity exercise are attenuated in middle-aged relative to young individuals. Further study is warranted to determine whether acute exercise-induced cardiac perturbations alter the adaptive myocardial remodeling response. [ABSTRACT FROM AUTHOR]

Aims Strenuous endurance exercise acutely increases myocardial wall stress and evokes transient functional cardiac perturbations. However, it is unclear whether exercise-induced functional cardiac disturbances are ubiquitous throughout the myocardium or are segment specific. The aim of this study was to examine the influence of high-intensity endurance exercise on global and segmental left (LV) and right (RV) ventricular tissue deformation (strain). Methods and results Echocardiography was used to measure strain in 23 active men (age: 28 ± 2 years; VO2 peak: 4.5 ± 0.7 L -1) at rest and during a standardized low-intensity exercise challenge, before and after a 90-min high-intensity endurance cycling intervention. Following the cycling intervention, LV and RV global strain decreased at rest (LV: -18.4 ± 0.4% vs. -17.7 ± 0.4%, P < 0.05; RV: -27.6 ± 0.7% vs. -26.4 ± 0.6%, P < 0.05) and by a greater extent during the low-intensity exercise challenge (LV: -21.3 ± 0.4% vs. -19.2 ± 0.5%, P < 0.01; RV: -28.4 ± 0.8% vs. -23.5 ± 0.9%, P < 0.01). Reductions in LV strain were unique to regions of RV attachment (e.g. LV septum: -24.4 ± 0.5% vs. -21.4 ± 0.6%, P < 0.01) with lateral (-18.9 ± 0.4% vs. -18.4 ± 0.5%) and posterior segments (-19.5 ± 0.4% vs. -18.8 ± 0.7%) unaffected. Similarly, augmentation of strain from rest to exercise was abolished in the RV free wall (-1.1 ± 1.0% vs. 2.9 ± 1.2%, P < 0.01), reduced in the septum (-4.6 ± 0.4% vs. -2.4 ± 0.5%, P < 0.01), and unchanged in the lateral (-1.2 ± 0.6% vs. -0.9 ± 0.6%) and posterior walls (-1.7 ± 0.6% vs. -1.3 ± 0.7%). Conclusion Changes in ventricular strain following high-intensity exercise are more profound in the right ventricle than in the left ventricle. Reductions in LV strain were unique to the septal myocardium and may reflect ventricular interactions secondary to exercise-induced RV dysfunction. [ABSTRACT FROM AUTHOR]